Double Walled Octahedron (Zen Magnets)

This video shows how to build a double-walled octahedron using Zen Magnets. It's a particularly simple build for a particularly lovely and symmetric shape, and it can be built (for edge counts 4 and 7) using only a single set of Zen Magnets. Here's a table showing the number of magnets needed for each size:

edge, layer 1, layer 2, magnets
4, 2 x 2, 3 x 2, 44
7, 2 x 5, 2 x 6, 212
10, 2 x 8, 2 x 9, 524
13, 2 x 11, 2 x 12, 980
16, 2 x 14, 2 x 15, 1580
19, 2 x 17, 2 x 18, 2324
22, 2 x 20, 2 x 21, 3212
25, 2 x 23, 2 x 24, 4244
28, 2 x 26, 2 x 27, 5420
31, 2 x 29, 2 x 30, 6740
34, 2 x 32, 2 x 33, 8204
37, 2 x 35, 2 x 36, 9812
40, 2 x 38, 2 x 39, 11564
43, 2 x 41, 2 x 42, 13460
46, 2 x 44, 2 x 45, 15500
49, 2 x 47, 2 x 48, 17684
52, 2 x 50, 2 x 51, 20012
55, 2 x 53, 2 x 54, 22484
58, 2 x 56, 2 x 57, 25100
61, 2 x 59, 2 x 60, 27860
64, 2 x 62, 2 x 63, 30764
67, 2 x 65, 2 x 66, 33812
70, 2 x 68, 2 x 69, 37004
73, 2 x 71, 2 x 72, 40340
76, 2 x 74, 2 x 75, 43820
79, 2 x 77, 2 x 78, 47444
82, 2 x 80, 2 x 81, 51212
85, 2 x 83, 2 x 84, 55124
88, 2 x 86, 2 x 87, 59180
91, 2 x 89, 2 x 90, 63380
94, 2 x 92, 2 x 93, 67724
97, 2 x 95, 2 x 96, 72212
100, 2 x 98, 2 x 99, 76844